Process of producing artificial threads



Patented Jan. 3, 1939 UNl'lEl) STATES PATENT OFFICE PROCESS OF PRODUCINGARTIFICIAL THREADS Karl Weissenberg, BerIin ZehIendorI, and BrunoBabinowitsch, Berlin, Germany; said Rabinowltsch assignor to saidWeissenberg No Drawing. Application January 17, 1930, Se-

rial No. 421,583. In Germany February 18,

1% Claims.

a fibrous internal structure under Roentgen ray examination, hightensile strength and fine titre;

' and it further comprises processes wherein finished or preformedartificial threads, films and the like are simultaneously swollen andsubstantially stretched to produce such a fibrous structure and finertitre, together with enhanced tensile strength and other desirableimprovement; all as more fully hereinafter set forth and as claimed.

Artificial threads, films and the like, heretofore made from celluloseesters and ethers, are in the form of dry gels; and arecharacteristically different from natural fibrous textiles, such ascotton, etc., in that they are of amorphous and non-fibrous structure..These non-fibrous artificial threads and the like are made by variousprocesses. In some processes in which artificial threads are made fromcellulose esters and ethers by dry spinning, the threads are drawn asthey leave the spinning cell, giving a slight stretching of the thread.This stretching does not exceed the normal limit of elongation, beingabout 25 per cent. In such cases there is no substantial improvement inthe thread, such as increased strength. In other known processes, insome instances the finished thread is given a limited stretching, notexceeding 25 percent. This stretching likewise does not give anysubstantial improvement in titre and in strength. In other processes, ithas been sought to improve yarns prepared from cellulose esters bytreating the finished threador yarn with acetic acid and then subjectingthe thread to a slight stretching and finally removing the acid whilemaintaining or increasing the tension of the thread. Again, in stillother processes, such threads are treated in certain swelling baths, andthe swollen thread slightly stretched; the stretching not exceedingabout 100 per cent. However, in such cases the subsequent stretching ofthe cellulose thread is necessarily limited to the extension mentioned,as during this stretching the swollen body rapidly loses the greaterpart of its plastic properties, so that further stretching withoutrupture is practically impossible.

By none of these prior processes is it possible to obtain the new andimproved artificial threads and the like, such as are'made in thepresent invention.

Wehave now found that such threads and the like may be given a fibrousinternal structure, as evinced by Roentgen ray examination, withsubstantial improvement in titre and tensile strength, by new processesdiscovered by us. Our new processes may be applied to any preformed orfinished thread, film or like material made .from cellulose esters andethers or similar compounds, preformed or finished materials beingadvantageously dry. In our process, such finished or preformed threadsand the like aresimultaneously swollen and substantially stretched, thestretching being above 200 per cent elongation; stretching to, at least,200 per cent giving substantial improvement in the thread and. producingthe desired characteristics. This stretching may be to an unlimitedextent; to.

1,000 per cent or more.

Our new process may be applied to threads and the like made fromcellulose esters and ethers, such as nitrocellulose, acetyl celluloseand the like. It may also be applied to such articles made from viscose(xanthate), the process being somewhat modified for this type ofmaterial.

, Tests have shown that an already prepared and dried thread or film,that is, one in the dry gel condition and freed from all solvent, can beconsiderably improved if it be greatly stretched after swelling whilestill retaining the gel condition. A quite general improvement takesplace in this, which embraces above all the strength, the fineness andthe lustre, it'being possible by a suitable choice of theconditions ofworking, to influence one or more of these properties above the others.According to the invention, the process for the improvement ofartificial threads of cellulose esters and ethers consequently consistsin the threads being changed from their original condition which underthe Roentgen rays appear amorphous, by mechanical treatment incombination with chemically inert steam or liquid baths, withoutchemical change, into the axially arranged crystalline condition. Themechanical treatment which can be carried out in the chemgreat deal over200 per cent and even up to several 1000 per cent. This astonishinglylarge stretching capacity is also present even with nonuniform threadswith largely varying sections, and the stretching then comprises notonly the parts with thin initial sections but also the whole thread, sothat a remarkably uniform thread is produced from the original uneventhread.

The speed of stretching must here be so suited to the other factorsinfluencing the softening, viz: temperature, pressure, composition andconcentration, that the weakening accompanying the stretching of themoist thread by the reduction of the section is at least compensated bythe strengthening oi this section simultaneously attained in the bath.To regulate the lustre, the choice of the baths and the manner of thestretching may be correlated together. In particular directly after thestretching, the threads may be treated with salt baths. By suitablemutual correlation of the concentration, the solution additions, thepressure, the temperature, and the speed of drawing 011', an increase inthe tensile strength or resistance to rupture of the dried thread by atleast 100 per cent is obtained.

For the technical utilization of the improving process, the fact is ofparticular importance that it is not limited to single threads but maybe just as well used on twisted artificial threads, hanks, wovenmaterial and films, with i! necessary the simultaneous shaping anddyeing, without the separate parts adhering together,

The advantages of the new improving process consist in the production ofartificial threads,

woven materials, films and the like, of cellulose esters and ethers (forexample, cellulose acetate, nitrate, xanthate, etc.) being madepossible, these having a fineness and resistance to rupture in the dryand wet state not hitherto at-' tained by any process, and in the lustreof these productions being capable of regulation. The reduction of thecapacity of swelling andthe improvement in the wet strength is alsoworthy of note. It is thus possible to produce from coarse comparativelycheap artificial threads, because they are lighter and are produced ingreater quantities, or from similar woven materials or and this withoutdifiiculty.

It is clear that with the new improving treatment, the knownsupplementary treatments may be combined, such as are usual withartificial threads, woven materials or films for various purposes. Forexample, there may be simply mentioned: The production of staple fibers,of crepe threads, curling, dyeing, regulation of lustre on stretching bythe aid of weak acids, the treatment with weak alkaline media for thepurpose of removing the last traces of acid, or the treatment withdirect electric current, and the like. Furthermore, after theimprovement has taken place, the goods may be regenerated by knownprocesses to cellulose and for example the acetyl cellulose threads bede-acetylized by dipping in alcoholic potash lye. This regenerationtreatment can be carried out with the stretching in the samecrystallization bath.

As crystallization baths which, in combination with the mechanicaltreatment described, produce the improvement of the artificial thread,woven material or films, chemically inert vapour or liquid baths aresuitable which consist of a non-solvent and a solvent, preferably anorganic solvent, the solvent eflect of which, by the choice oi. suitabletemperatures or pressures, but in particular of additions, for exampleprecipitants, is, with an incease in the swelling capacity, reduceduntil a prepared artificial thread 01' a cellulose-ester or etherbecomes capable of stretching in the bath to a practically unlimitedextent, at any rate considerably over the natural limit of plasticity.As chemically inert baths those are in particular understood whichneither produce a chemical change in the 'material stretched, nor'areotherwise chemically active, as is for example the case with acids.Mixtures of pure or commercial dioxane (diethylene dioxid) containingethylene acetal, and water or mixtures of acetone and carbontetrachloride have proved themselves as particularly suitablecrystallization baths for acetyl cellulose threads and films.

As one component of the crystallization bath, as already mentioned,exercises a dissolving effect on the goods being stretched and the othercomponent a precipitating cheat, or behaves inertly, it is oftendifllcult, on account of these opposing properties, to attain asufficiently good mixing of the two components since temperatures orconcentration conditions come into consideration, so that the choice isextraordinarily limited. In addition to this, one of the two componentsis generally absorbed in the crystallization treatment bythe goods beingcrystallized in preference to the other and is withdrawn with the goods,and this has as a consequence an alteration of the concentration in thebath, and under certain circumstances a separation of the mixture. Thesedisadvantages can be overcome according to the invention by adding todiflicultly miscible 'or immiscible systems, substances which produce acomplete mixing at least within the limits of temperature andconcentration coming into consideration. Such additions or blendedagents may themselves act as solvents or be inert. As solvent componentsof such three or more component mixtures, it isdesirable to use organicliquids, in particular the lower members 01 the homologous series ofallphatic esters, ketones, ketoles; and various heterocyclic compounds,as, for example, furfuran and pyridine come into consideration, while asinert components, water or a precipitant for the crystallization goods,soluble in the solvent com-- ponents, come into question.

Particularly advantageous for the purposes of the invention, have beenproved solvent and inert or precipitant components which enter intomolecular combination with each other. As most of the solvent componentsare easily volatllized organic bodies of. low flash point it isdesirable for reasons of safety, especially with the use ofcrystallization goods also easily inflammable, as for example,nitro-cellulose, to reduce the flash point of the baths. For thispurpose a further substance acting in this manner can be added to thebaths. If necessary this may also facilitate the miscibility oi thecomponents in the sense of the invention.

The invention oiiers the advantage that a regeneration of the usedcrystallization baths by producing an intentional separation after theremoval of the addition, is extraordinarily 'facilitated. A furtheradvantage consists in that there is a large field oflered in the choiceof the conditions in the temperature and concentration.

As already mentioned in the introduction, the production 01' an at leastpartially crystalline structure with artificial threads or films otcellulose esters and ethers can also be attained during the producingprocess thereof (crystallization spinning process).

Of all the hitherto known spinning processes for artificial threads,only that one permits an improvement combined with the actual spinningby excessive stretching, in which the cellulose esters and etherscontained in the spinning solution are regenerated into hydratecellulose during the stretching. This holds good in particular for theprocess of production for viscose silk and cuprous silk. With the otherdry or wet spinning processes on the other hand it has not been possibleto effect any improvement at all by stretch spinning. It has now beenproved that any spinning process whatever can be changed into acrystallization spinning process if the excessive stretching improvingthe spun goods is carried out in a crystallization bath, in which aprepared air dried thread can be stretched, with improvement. Thesecrystallization baths do not need to exert a regenerative action on thethreads produced. It is only necessary that the stretched goods have acertain swelling condition imparted thereto and that the draw off speed,temperature and pressure be suitably adjusted together. The newcrystallization spinning process can be carried out both in theso-cailed single bath as also in the so-called multiple bath process. Inthe latter case, with viscose the stretching takes place in one or morebaths which do not contain subv ethers, the stretching can be carriedout with or without regeneration. The selection of the swelling mediummust be controlled in thefirst place by the nature of the threads to beproduced. Thus for artificial threads of cellulose esters or ethersorganic non-acid solvents have been found particularly suitable whichexert their action in the vapour condition also, so that insteadof thesecond bath a vapour treatment can be employed.

- strengthening of the thread an extraordinary improvement issimultaneously obtained. Artificial threads are obtained in this way upto a fraction of a denier with strength of between 300 to 700 g/ 100den. The products obtained from cellulose esters and ethers are,contrary to those made in the known ways, largely crystallized andarranged axially. By the selection of the swelling medium, and thelength and speed of the stretching it is possible to considerablyinfluence the lustre of the products, when if necessary a supplementarytreatment. with salt baths may 'follow directly after the stretching.

It is not absolutely necessary for. the stretching to take place in thecrystallization bath itself. The thread can be subjected to thestretching directly after leaving the bath. The swelling action of thebath'or vapour may be regulated within wide limits by, in addition tothe alteration of the concentration, the choice of the temperature andthe duration of. the swelling. Simikinds as for example glue, albuminoussubstances,

etc., can be also carried out.

In the same way as with artificial threads,

films may also be produced and shaped accord-,

ing to the new process, with afar reaching improvement.

Furthermore, other properties, in particular the heat conductivity ofthe products can also be influenced by the incorporation of suitablesubstances duringthe improving treatment. Thus, for instance theswelling me dium taken up by the goods being stretched can betransformed by heating or by a vacuum treatment into the vapour state.The expansion thus taking place efiects at the same time a mechanicalstressing of the goods being stretched in the above-mentioned sensecrossways to the stretching direction and therefore a furtherextensibility.

Known additions as for example for the purpose of increasing theplasticity lustre, colour and the like, can be added to the spinningsolution or to the swelling bath or to both.

Examples Example 1.-A singlethread' acetyl cellulose silk of 10 denierswas swollen in a bath of equal parts of commercial dioxane (diethylenedioxid) and water and then stretched to 30 times the length, that is to0.33 den. The time- 0f stretching lasted 8 seconds; There consequentlyresulted an improvement coefficient (that is init'ra standard to finalstandard) of 30.

Example 2.--A thread of 800 parallel arranged threads spun from aspinning solution of 20 parts of acetyl cellulose and parts of dioxaneand having a standard of 5.7 den. and a resistance to tearing of 140 g/den. after drying is swelled in a mixture of equal parts of dioxane andwater and then stretched for 12 minutes-to 20 times the length. This wasthen washed with a 30 percent sodium sulphate solution and .cold water.The stretched, dry thread has a standard of 0.285 den., and a strengthof 610 g/100 den. The improvement co'eiiicient amounted consequently forthe titre to 20 and that for the strength to 4.35.

Example 3.'The same initial material as in Example 2 was swelled in abath of equal parts of dioxane and water and stretched for 12 minutes to11.1 times the length. After washing with cold water and drying a threadwas obtained of 0.51 den. and 616 g/100 den. The improvement coeflicientamounted consequently for the titre to' 11.10 and for the strength to4.40.

Example 4.The same initial material as in Example 3 resulted, with 11.1times the stretching in a bath of equal parts of dioxane and water andsubsequent washing with cold water in a resistance to rupture of 616 g/100 den. as Well as an extensibility of 9.4 per cent, while the initialmaterial had a strength of g/ 100 den. and an extensibility of 20 percent.

Example 5.The initial material used in Example 2: gave with 20 times thestretching in the dioxane water mixture and subsequent washing with 30per cent sodium sulphate solution and cold water, a resistance torupture of 610 g/ 100 den., and an extensibility of 10 per cent, whilethe initial material had a resistance to rupture of 140 g/l00 den. andan extensibility of 20 per cent.

Example 6.A thread spun from 20 parts acetyl cellulose, 40 parts dioxaneand 40 parts acetone was stretched in a bath of equal parts of acetoneand carbon tetrachloride, for 9 minutes, from 12.05 to 5.2 den. that, isto an extent of 2.3 times. After washing with cold water and dryarewashed with cold water.

Example 8.A slightly less lustre is given by the process under theconditions of Example 2.

Example 9.A matted silk lustre and soft touch is given by treatment of acommercial acetate silk (12 twisted single threads of 5.2 den.), if 160such threads twisted and lying in parallel are stretched for 8 minutesin a bath of equal parts of dioxane and water to an extent of 3.06times, the titre falling from 5.2 to 1.7. I

This is followed by washing with hot. water (80 C.).

ExampIeIOP-A perfectly matt thread is given by the same commercialacetate silk as in Example 9 if it is stretched in a bath of equal partsof dioxane and water for 8 minutes to 3.24 times the length, and thenwashed with cold water.

. The thread produced is characterized by its marked soft and down-likecharacter.

Example 11.A similar appearance but with a slightly harder touch isshown by a thread which is stretched as in Example 10 but is washed outwith methyl alcohol.

Example 12.-A down-like character but greater lustre is given by athread stretched according to Example 11, washed out with a 30 per centsodium sulphate solution and hot water (80 Example 13.-The acetylcellulose threads stretched as in Example 3 are in known mannerde-acetylized by steeping them for 12 hours under tension in alcoholicpotash lye, which contains 32 g. of caustic potash to the litre. Thecellulosethreads so regenerated show an addi- "tional improvement of thestrength properties.

Example 14.Acetyl cellulose threads of den. are during stretchingsimutaneously deacetylized in the 50 per cent dioxane bath, the knownadditions for de-acetylizing being made to the dioxane bath. The threadsproduced of regenerated cellulose show an improvement of the strengthproperties.

Example 15.--An acetyl cellulose thread is carried through a 50 per centdioxane solution and then passed through a funnel through which.quicksilver flows in the same direction. The

quicksilver exercises a strangling effect on the thread which favoursthe stretching. The titre of the thread is consequently still furtherreduced.

Example 16.A lustrous acetyl celulose thread is first stretched in abath of 48. parts dioxane and 52 parts of water to 4 times the length.It is then washed with cold water and allowed to dry. A completely mattthread is thus produced. If this thread is new again stretched-in a 50per cent dioxane solution to a further 5 times the length, that, is,altogether to 20 times the original length, then after washing andtreating with 30 per cent sodium sulphate solution,

the original lustre is recovered, while'the strength properties as wellas the titre are considerab improved.

Example 17.The treatment described in Example 18 is altered by one stageof the two part processes being carried out by rolling.

Example 18.-The treatment described in. Example 16 is altered by thesecond partial treatment being carried out in a swelling bath with addedde-acetylizing media.

Example 19.--A suitable crystallization bath for artificial threads orfilms of cellulose ethers or esters at 20 C. has the followingcomposition:

1. Solvent component: vol. methylethyl ketone (or acetone),

2. Inert or precipitating component: 10 vol. water,

3. The addition producing miscibility: 1 vol.

alcohol. The alcohol serves as a blending agent, for the ketone-watermixture. Example 20.--A per cent acetyl cellulose solution in pure orcommercial dioxane is spun through a nozzle for 80 threadsin acrystallization spinning bath of approximately 50 per cent dioxane and50 per cent water, with a speed of 5.5 g. spinning solution per minute(corresponding to 1.1 g. acetyl cellulose per minute) with a taking oil.speed by the stretching roller of 200-300 metres per minute. There isproduced a total thread of 33 den. thickness which is composed of 80separate threads of 0.4 den. By changing the concentration of thecrystallizationbath, the plasticity of the thread may be regulatedwithin wide limits. I 1

What we claim is:-

1. A process of preparing artificial thread formed of an organicderivative of cellulose and characterized by a fine denier, high tensilestrength and a fibrous structure under Roentgen ray examination whichcomprises treating a thread formed of an organic derivative of cellulosewith a bath comprising dioxane and water in such proportions as to swelland plasticize lose with a swelling bath comprising approximately equalparts by weight of dioxane and water and stretching the thread until thelength thereof is at least 200% of the original length. 3. A swellingbath for treating artificial thread formed of an organic derivative ofcellulose and comprising dioxane and water in such proportions as toswell and plasticize said thread,

whereby said thread can be stretched until the length thereof is atleast 200% of the original length.

4. A swelling bath for treating artificial thread formed of an organicderivative of cellulose and comprising dioxane, ethylene acetal andwater in such proportions as to swell and plasticize said thread,whereby said thread can be stretched until the length thereof is atleast 200% of the v original length.

5.. A swelling bath for treating artificial thread formed of an organicderivative of cellulose and comprising approximately equal parts byweight of dioxane and w'ater'to swell and plasticize the thread, wherebythe thread can be stretched until it is at least 200% of the originallength.

6. A swelling bath for treating artificial thread formed of an organicderivative of cellulose and comprising approximately equal parts byweight of acetone and carbon tetrachloride to swell and plasticize thethread, whereby the thread can be stretched until it is at least 200%ofthe original length.

7. A process of preparing artificial thread formed of a cellulosederivative and characterized by a fine denier, high tensile strength anda fibrous internal structure under Roentgen ray examination whichcomprises treating a thread formed of an organic derivative of cellulosewith a swelling bath comprising equal parts by weight of acetone andcarbon tetrachloride and stretching the thread until the length thereofis at least 200% of the original length.

8. A method of preparing artificial thread characterized by a finedenier and 'a high tensile strength which comprises spinning a solutionof an organic derivative of cellulose into a bath comprising dioxane andwater and taking off the thread at a speed sumcient to stretch thefreshly produced yarn at least 100% of its original length.

9; A method of preparing artificial threadcient to stretch the freshlyproduced yarn at least 100% of its original length.

10. A method of preparing artificial thread characterized by a finedenier and a high tensile strength which comprises spinning a 20%solution of cellulose acetate in dioxane into a bath comprising dioxaneand water and taking ofi.

the thread at a speed sufiicient to stretch the freshly produced yarn atleast 100% of its original length. I

11. A method of preparing artificial thread characterized by a finedenier and a high tensile strength which comprises spinning a 20%solution of cellulose acetate in dioxane into a bath comprisingapproximately equal parts by weight of dioxane and water and taking oilthe thread at a speed sufiicient to stretch the freshly produced yarn atleast 100% of its original length. '12. Process for the manufacture. ofartificial filaments, threads. yarns, ribbons and like prod- -ucts,-which comprises extruding a solution of cellulose acetate in dioxanethrough a shaping device into an aqueous solution of dioxane, stretchingthe products continuously with their production, and thereafter dryingthe products.

KARL WEISSENBERG. BRUNO RAIBINOWITSCH.

